Stabilized biodiesel fuel compositions

ABSTRACT

Disclosed are stabilized biodiesel fuel compositions, which compositions comprise a biodiesel fuel, for example the methyl esters of the fatty acids of rapeseed or soy oil, which compositions comprise
     a biodiesel fuel and   an effective stabilizing amount of a combination of   i) one or more compounds selected from the group consisting of the sterically hindered phenolic antioxidants and   ii) one or more compounds selected from the group consisting of the triazole metal deactivators.

This application claims benefit of U.S. provisional application No. 60/861,194, filed Nov. 27, 2006, which is incorporated by reference.

The present invention is aimed at biodiesel fuel (or bio-fuel) compositions, stabilized against the deleterious effects of heat, light, oxygen and metals by an effective amount of a combination of one or more compounds selected from the group consisting of the sterically hindered phenolic antioxidants and one or more compounds selected from the group consisting of the triazole metal deactivators.

BACKGROUND

WO2004055141 teaches the stabilization of fats, oils and food. The stabilizers are selected from the group consisting of the 3-arylbenzofuranones, long chain N,N-dialkylhydroxylamines, substituted hydroxylamines, nitrones and amine oxides.

EP1486555, EP1484387 and EP1484388 disclose a low corrosive fuel composition for use in a blue flame burner or an optimized yellow flame burner of a boiler.

U.S. Pat. No. 4,701,273 is aimed at lubricants and discloses combinations of a benzotriazole metal deactivator and phenolic antioxidants.

U.S. Pat. No. 6,410,490 teaches a composition comprising a hydrotreated oil or a hydrowaxed oil and a combination of a triazole metal deactivator, a phenolic antioxidant, an aromatic amine antioxidant, an alkyl phenoxy alkanoic acid and an N-acyl sarcosine derivative.

U.S. publication No. 2006/0218855 is aimed at a method of increasing the oxidation stability of biodiesel.

Biodeisel fuel is of increasing importance as a renewable fuel source. It may for example be employed as a fuel itself, or may be used in combination with diesel fuel.

SUMMARY

Disclosed are biodiesel fuel compositions stabilized against the deleterious effects of heat, light, oxygen and metals, which compositions comprise

a biodiesel fuel and

an effective stabilizing amount of a combination of

i) one or more compounds selected from the group consisting of the sterically hindered phenolic antioxidants and

ii) one or more compounds selected from the group consisting of the triazole metal deactivators.

Also disclosed is a process for the stabilization of a biodiesel fuel against the deleterious effects of heat, light, oxygen and metals, which process comprises

incorporating into a biodiesel fuel

an effective stabilizing amount of a combination of

i) one or more compounds selected from the group consisting of the sterically hindered phenolic antioxidants and

ii) one or more compounds selected from the group consisting of the triazole metal deactivators.

DETAILED DISCLOSURE

Biodiesel fuels are a renewable resource and are of increasing importance.

Biodiesel fuels typically comprise lower alkyl fatty acid esters, prepared for example by transesterifying triglycerides with lower alcohols, e.g. methanol or ethanol. A typical biodiesel fuel is the fatty acid methyl ester of rapeseed oil or of soy oil. Sources for biodiesel fuel include vegetable and animal sources. Recycled cooking oil may be a source of biodiesel fuel.

Biodiesel fuel and its preparation is taught for example in U.S. Pat. Nos. 5,578,090, 5,713,965, 5,891,203, 6,015,440, 6,174,501 and 6,398,707, the contents of which are hereby incorporated by reference.

Biodiesel fuel of the present invention for example comprises lower alkyl esters of a mixture of saturated and unsaturated straight chain fatty acids of from 12 to 22 carbon atoms, derived from vegetable or oleaginous seeds. The term “lower alkyl ester” means C₁-C₅ esters, in particular methyl and ethyl esters. The mixture of methyl esters of the saturated, monounsaturated and polyunsaturated C₁₆-C₂₂ fatty acids are what is typically known as “biodiesel” or “rapeseed methyl ester”.

Biodiesel fuel according to the present invention is 100% lower alkyl fatty acid ester, or is a combination of a lower alkyl fatty acid ester with diesel fuel. The present biodiesel fuel is for example from about 2 to about 98 weight percent fatty acid ester and from about 98 to about 2 weight percent diesel fuel. For example, the present biodiesel fuel is from about 10 to about 90 weight percent fatty acid ester and from about 90 to about 10 weight percent diesel fuel. For instance, the present biodiesel fuel is from about 25 to about 75 weight percent fatty acid ester and from about 75 to about 25 weight percent diesel fuel.

The hindered phenolic antioxidants are for example

1.1. Alkylated monophenols, for example 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(α-methylcyclohexyl)-4,6-dimethylphenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, nonylphenols which are linear or branched in the side chains, for example, 2,6-di-nonyl-4-methylphenol, 2,4-dimethyl-6-(1-methylundec-1-yl)phenol, 2,4-dimethyl-6-(1-methylheptadec-1-yl)phenol, 2,4-dimethyl-6-(1-methyltridec-1-yl)phenol and mixtures thereof.

1.2. Alkylthiomethylphenols, for example 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,4-dioctylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-di-dodecylthiomethyl-4-nonylphenol.

1.3. Hydroquinones and alkylated hydroquinones, for example 2,6-di-tert-butyl-4-methoxyphenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl stearate, bis-(3,5-di-tert-butyl-4-hydroxyphenyl)adipate.

1.4. Tocopherols, for example α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol and mixtures thereof (Vitamin E).

1.5. Hydroxylated thiodiphenyl ethers, for example 2,2′-thiobis(6-tert-butyl-4-methylphenol), 2,2′-thiobis(4-octylphenol), 4,4′-thiobis(6-tert-butyl-3-methylphenol), 4,4′-thiobis(6-tert-butyl-2-methylphenol), 4,4′-thiobis-(3,6-di-sec-amylphenol), 4,4′-bis(2,6-dimethyl-4-hydroxyphenyl)disulfide.

1.6. Alkylidenebisphenols, for example 2, 2′-methylenebis(6-tert-butyl-4-methylphenol), 2,2′-methylenebis(6-tert-butyl-4-ethylphenol), 2,2′-methylenebis[4-methyl-6-(α-methylcyclohexyl)phenol], 2,2′-methylenebis(4-methyl-6-cyclohexylphenol), 2,2′-methylenebis(6-nonyl-4-methylphenol), 2,2′-methylenebis(4,6-di-tert-butylphenol), 2,2′-ethylidenebis(4,6-di-tert-butylphenol), 2,2′-ethylidenebis(6-tert-butyl-4-isobutylphenol), 2,2′-methylenebis[6-α-methylbenzyl)-4-nonylphenol], 2,2′-methylenebis[6-(α,α-dimethylbenzyl)-4-nonylphenol], 4,4′-methylenebis(2,6-di-tert-butylphenol), 4,4′-methylenebis(6-tert-butyl-2-methylphenol), 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 1,1-bis(5-tert-butyl-4-hydroxy-2-methyl-phenyl)-3-n-dodecylmercaptobutane, ethylene glycol bis[3,3-bis(3-tert-butyl-4-hydroxyphenyl)butyrate], bis(3-tert-butyl-4-hydroxy-5-methyl-phenyl)dicyclopentadiene, bis[2-(3′tert-butyl-2-hydroxy-5-methylbenzyl)-6-tert-butyl-4-methylphenyl]terephthalate, 1,1-bis-(3,5-dimethyl-2-hydroxyphenyl)butane, 2,2-bis-(3,5-di-tert-butyl-4-hydroxyphenyl)propane, 2,2-bis-(5-tert-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercaptobutane, 1,1,5,5-tetra-(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane.

1.7. Benzyl compounds, for example 3, 5,3′,5′-tetra-tert-butyl-4,4′-dihydroxydibenzyl ether, octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate, tridecyl-4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)amine, 1,3,5-tri-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, di-(3,5-di-tert-butyl-4-hydroxybenzyl)sulfide, 3,5-di-tert-butyl-4-hydroxybenzyl-mercapto-acetic acid isooctyl ester, bis-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithiol terephthalate, 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, 3,5-di-tert-butyl-4-hydroxybenzyl-phosphoric acid dioctadecyl ester and 3,5-di-tert-butyl-4-hydroxybenzyl-phosphoric acid monoethyl ester, calcium-salt.

1.8. Hydroxybenzylated malonates, for example dioctadecyl-2,2-bis-(3,5-di-tert-butyl-2-hydroxybenzyl)-malonate, di-octadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)-malonate, di-dodecylmercaptoethyl-2,2-bis-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, bis[4-(1,1,3,3-tetramethylbutyl)phenyl]-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate.

1.9. Aromatic hydroxybenzyl compounds, for example 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol.

1.10. Triazine compounds, for example 2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine, 2,4,6-tris-(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,2,3-triazine, 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)-hexahydro-1,3,5-triazine, 1,3,5-tris(3,5-dicyclohexyl-4-hydroxybenzyl)isocyanurate.

1.11. Benzylphosphonates, for example dimethyl-2,5-di-tert-butyl-4-hydroxybenzylphosphonate, diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, the calcium salt of the monoethyl ester of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.

1.12. Acylaminophenols, for example 4-hydroxy-lauric acid anilide, 4-hydroxy-stearic acid anilide, 2,4-bis-octylmercapto-6-(3,5-tert-butyl-4-hydroxyanilino)-s-triazine and octyl-N-(3,5-di-tert-butyl-4-hydroxyphenyl)-carbamate.

1.13. Esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.14. Esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis-(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.15. Esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.16. Esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.17. Amides of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid e.g. N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexamethylenediamide, N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)trimethylenediamide, N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazide, N,N′-bis[2-(3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyloxy)ethyl]oxamide (Naugard®XL-1 supplied by Uniroyal).

For example, the present hindered phenolic compounds are selected from butylated phenol, butylated hydroxytoluene, butylated hydroxyanisole, tocopherol, benzylphosphonates, esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with mono- or polyhydric alcohols, esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols and esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or polyhydric alcohols.

For instance, the present hindered phenolic compounds are selected from 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol (BHT), 2,2′-methylene bis-(4,6-di-tert-butylphenol), 1,6-hexamethylene-bis-(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), ((3,5-bis(1,1-dimethylethyl)-4-hydroxphenyl)methylthio)acetic acid C₁₀-C₁₄ isoalkyl esters, 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid C₆-C₉alkyl esters, 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid methyl ester, tetrakis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionyloxymethyl)methane, thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate and 2,5-di-tert-butylhydroquinone.

For example, the present hindered phenolic antioxidants are selected from 2,6-di-tert-butylphenol, 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid methyl ester and tetrakis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionyloxymethyl)methane.

The present triazole metal deactivators are of the 1,2,4-triazole class or the benzotriazole class.

Metal deactivators of the 1,2,4-triazole class are disclosed for example in U.S. Pat. No. 4,734,209, the disclosure of which is hereby incorporated by reference.

The 1,2,4-triazole metal deactivators are for example of the formula (I)

where

R₁ and R₂ are the same or different and are hydrogen, C₁-C₂₀alkyl, C₃-C₂₀alkenyl, C₅-C₁₂cycloalkyl, C₇-C₁₃aralkyl, C₆-C₁₀aryl or hydroxy or R₁ and R₂, together with the nitrogen atom to which they are each attached may form a 5-, 6- or 7-membered heterocylic ring, or R₁ and R₂ are a group of formula

R₃X[(—R₄—)O]_(n)(—R₄)—

where

X is O, S or NR₃,

R₃ is hydrogen or C₁-C₂₀alkyl,

R₄ is C₁-C₁₂alkylene,

n is 0 or an integer from 1 to 6,

or one of R₁ and R₂ is a group of formula

or R₂ is a group of formula (II) and R₁ is a group of formula

—[R₄]_(n)—N(R₅)-A-[N(R₅)₂]_(m)

where

m is 0 or 1 and, when m is zero, A is a group of formula (II) and, when m is 1, A is alkylene or C₆-C₁₀ arylene and R₅ is a group of formula (II).

R₄ is for example a C₁-C₆alkylene group, for instance a C₂-C₃alkylene.

n is for instance 0, 1, 2, 3, 4, 5 or 6.

Specific compounds of present formula (I) include:

-   1-(or 4)-(dimethylaminomethyl)triazole, -   1-(or 4)-(diethylaminomethyl)triazole, -   1-(or 4)-(di-isopropylaminomethyl)triazole, -   1-(or 4)-(di-n-butylaminomethyl)triazole, -   1-(or 4)-(di-n-hexylaminomethyl)triazole, -   1-(or 4)-(di-isooctylaminomethyl)triazole, -   1-(or 4)-(di-(2-ethylhexyl)aminomethyl)triazole, -   1-(or 4)-(di-n-octylaminomethyl)triazole, -   1-(or 4)-(di-n-decylaminomethyl)triazole, -   1-(or 4)-(di-n-dodecylaminomethyl)triazole, -   1-(or 4)-(di-n-octadecylaminomethyl)triazole, -   1-(or 4)-(di-n-eicosylaminomethyl)triazole, -   1-(or 4)-[di-(prop-2′-enyl)aminomethyl]triazole, -   1-(or 4)-[di-(but-2′-enyl)aminomethyl]triazole, -   1-(or 4)-[di-(eicos-2′-enyl)aminomethyl]triazole, -   1-(or 4)-(di-cyclohexylaminomethyl)triazole, -   1-(or 4)-(di-benzylaminomethyl)triazole, -   1-(or 4)-(di-phenylaminomethyl)triazole, -   1-(or 4)-(4′-morpholinomethyl)triazole, -   1-(or 4)-(1′-pyrrolidinomethyl)triazole, -   1-(or 4)-(1′-piperidinomethyl)triazole, -   1-(or 4)-(1′-perhydroroazepinomethyl)triazole, -   1-(or 4)-(2′,2″-dihydroxyethyl)aminomethyl]triazole, -   1-(or 4)-(dibutoxypropyl-aminomethyl)triazole, -   1-(or 4)-(dibutylthiopropyl-aminomethyl)triazole, -   1-(or 4)-(di-butylaminopropyl-aminomethyl)triazole, -   N,N-bis-(1- or 4-triazolylmethyl)laurylamine, -   N,N-bis-(1- or 4-triazolylmethyl)oleylamine, -   N,N-bis-(1- or 4-triazolylmethyl)ethanolamine and -   N,N,N′,N′-tetra(1- or 4-triazolylmethyl)ethylene diamine.

The present compound of formula (I) is for example 1-(di-isooctylaminomethyl)triazole, that is 1-(di-isooctylaminomethyl)-1,2,4-triazole, or is 1-(di-(2-ethylhexyl)aminomethyl)1,2,4-triazole.

The benzotriazole metal deactivators are for example those disclosed in U.S. Pat. Nos. 5,032,300 and 5,171,463, the disclosures of which are hereby incorporated by reference.

The benzotriazole metal deactivators are for example of the formula (III)

where

R₆ is C₁-C₁₂alkyl,

R₇ is C₁-C₁₂alkyl, C₁-C₁₂alkyl interrupted by one or more O atoms or is C₅-C₁₂cycloalkyl and

R₈ and R₉ are hydrogen or methyl.

Specific examples of compounds of formula (III) include:

-   1-(2-methoxyprop-2-yl)tolyltriazole, -   1-(1-methoxyethyl)tolyltriazole, -   1-(1-methoxpropyl)tolyltriazole, -   1-(1-isobutoxybutyl)tolyltriazole, -   1-(1-tert-butoxybutyl)tolyltriazole, -   1-(1-hexyloxybutyl)tolyltriazole, -   1-(1-octyloxybutyl)tolyltriazole, -   1-(1-butoxy-2-methylpropyl)tolyltriazole, -   1-(1-dodecyloxybutyl)tolyltriazole, -   1-(1-isopropyloxyethyl)tolyltriazole, -   1-(1-isopropyloxypropyl)tolyltriazole, -   1-(1-isopropyloxybutyl)tolyltriazole, -   1-(1-cyclohexyloxypropyl)tolyltriazole, -   1-(1-cyclohexyloxyheptyl)tolyltriazole, -   1-(1-cyclohexyloxybutyl)tolyltriazole, -   1-[1-(2-methoxyethoxy)butyl]tolyltriazole and -   1-[1-(2-ethoxyethoxy)butyl]tolyltriazole.

The present compound of formula (III) is for example 1-(2-methoxyprop-2-yl)tolyltriazole, 1-(1-cyclohexyloxypropyl)tolyltriazole, 1-(1-cyclohexyloxyheptyl)tolyltriazole or 1-(1-cyclohexyloxybutyl)tolyltriazole.

(1-(2-methoxyprop-2-yl)tolyltriazole is

1-(1-cyclohexyloxyheptyl)tolyltriazole is

The benzotriazole metal deactivators may also be for example those disclosed in U.S. Pat. Nos. 5,580,482 and 6,410,490, the disclosures of which are hereby incorporated by reference.

The benzotriazole metal deactivators are for example of the formula (IV)

where

R₁₀ is hydrogen or C₁-C₁₂alkyl,

R₁₁ and R₁₂ are the same or different and are hydrogen, C₁-C₂₀alkyl, C₃-C₂₀alkenyl, C₅-C₁₂cycloalkyl, C₇-C₁₃aralkyl, C₆-C₁₀aryl or hydroxy or R₁₁ and R₁₂, together with the nitrogen atom to which they are each attached may form a 5-, 6- or 7-membered heterocylic ring, or R₁₁ and R₁₂ are a group of formula

R₁₃X[(—R₁₄—)O]_(n)(—R₁₄)—

where

X is O, S or NR₁₃,

R₁₃ is hydrogen or C₁-C₂₀alkyl,

R₁₄ is C₁-C₁₂alkylene,

n is 0 or an integer from 1 to 6,

or one of R₁₁ and R₁₂ is a group of formula

or R₁₂ is a group of formula (II) and R₁₁ is a group of formula

—[R₁₄]_(n)—N(R₁₅)-A-[N(R₁₅)₂]_(m)

where

m is 0 or 1 and, when m is zero, A is a group of formula (II) and, when m is 1, A is alkylene or C₆-C₁₀arylene and R₁₅ is a group of formula (II).

The benzotriazoles of component (IV) are for example

-   4-(or 5)-methyl-1-(di(2-ethylhexyl)-aminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(dimethylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(diethylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(di-isopropylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(di-n-butylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(di-n-hexylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(di-isooctylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(di-n-octylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(di-n-decylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(di-n-dodecylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(di-n-octadecylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(di-n-eicosylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-[di-(prop-2′-enyl)aminomethyl]-benzotriazole, -   4-(or 5)-methyl-1-[di-(but-2′-enyl)aminomethyl]-benzotriazole, -   4-(or 5)-methyl-1-[di-(eicos-2′-enyl)aminomethyl]-benzotriazole, -   4-(or 5)-methyl-1-(di-cyclohexylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(di-benzylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(di-phenylaminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(4′-morpholinomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(1′-pyrrolidinomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(1′-piperidinomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(1′-perhydroroazepinomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(2′,2″-dihydroxyethyl)aminomethyl]-benzotriazole, -   4-(or 5)-methyl-1-(dibutoxypropyl-aminomethyl)-benzotriazole, -   4-(or 5)-methyl-1-(dibutylthiopropyl-aminomethyl)-benzotriazole and -   4-(or 5)-methyl-1-(di-butylaminopropyl-aminomethyl)-benzotriazole.

The present benzotriazoles of formula (IV) are for example 4-(or 5)-methyl-1-(di(2-ethylhexyl)-aminomethyl)-benzotriazole or 4-(or 5)-methyl-1-(di-isooctylaminomethyl)-benzotriazole.

Alkyl is a branched or unbranched radical such as, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl or docosyl.

Alkenyl is a branched or unbranched radical such as, for example, propenyl, 2-butenyl, 3-butenyl, isobutenyl, n-2,4-pentadienyl, 3-methyl-2-butenyl, n-2-octenyl, n-2-dodecenyl, isododecenyl, oleyl, n-2-octadecenyl or n-4-octadecenyl. Preference is given to alkenyl having 3 to 18, especially 3 to 12, for example 3 to 6, in particular 3 to 4 carbon atoms.

Cycloalkyl is, for example, cyclopentyl, methylcyclopentyl, dimethylcyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, trimethylcyclohexyl, tert-butylcyclohexyl, cycloheptyl or cyclooctyl. Preference is given to cyclohexyl and tert-butylcyclohexyl.

Aralkyl is, for example, benzyl, α-methylbenzyl, α,α-dimethylbenzyl or 2-phenylethyl. Benzyl and α,α-dimethylbenzyl are preferred.

Aryl is for example phenyl or naphthyl, but also comprised are C₁-C₄alkyl substituted phenyl, C₁-C₄alkoxy substituted phenyl, hydroxy, halogen or nitro substituted phenyl. Examples for alkyl substituted phenyl are ethylbenzene, toluene, xylene and its isomers, mesitylene or isopropylbenzene. Halogen substituted phenyl is for example dichlorobenzene or bromotoluene.

Alkylene is a branched or unbranched radical such as, for example, methylene, ethyllene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethyllene, octamethylene, decamethylene, dodecamethylene or octadecamethylene. Preference is given to C₁-C₈alkylene.

Arylene is a divalent aryl, for instance phenylene or naphthalene.

Components i) and ii) each are employed at levels of about 5 ppm to about 5000 ppm, for example from about 50 ppm to about 5000 ppm, for example from about 100 to about 5000 ppm by weight, based on the weight of the biodiesel fuel. For example, each of the present additives are present from about 150 to about 4000 ppm, from about 200 to about 3000 ppm, or from about 250 to about 2500 ppm by weight, based on the weight of the biodiesel fuel. In certain instances, the levels may be as high as about 1%, about 2% or about 3% by weight, based on the weight of the biodiesel fuel.

The present stabilized biodiesel fuels exhibit increased storage stability vs. unstabilized samples. Degradation of biodiesel fuels under the conditions of heat, light, oxygen or metals is observed by the formation of carboxylic acids, peroxides, aldehydes and alcohols. Degradation under the conditions of metals means metal contamination.

The present stabilized biodiesel fuels may also contain known metal chelating compounds. The known metal chelating compounds include hydroxycarboxylic acid chelators such as citric acid, hydroxycarboxylic acid ester chelators such as triethyl citrate and monostearyl citrate, Schiff bases such as N,N,-disalicylidene-1,2-propanediamine (DMD), aminoalcohols such as triethanolamine and N-hydroxyethylethylenediamine, polyamines such as ethylenediamine and diethylenetriamine and aminocarboxylic acid chelators such as ethylenediaminetetraacetic acid (EDTA). Mixtures of these compounds may also be employed.

The present stabilized biodiesel fuels may also contain one or more stabilizers selected from the group consisting of the 3-arylbenzofuranone stabilizers and the hindered amine light stabilizers. For instance, stabilizers as disclosed in U.S. provisional app. No. 60/756,090, filed Jan. 4, 2006, the disclosure of which is hereby incorporated by reference.

The 3-arylbenzofuranones antioxidants are for example those disclosed in U.S. Pat. Nos. 4,325,863; U.S. Pat. No. 4,388,244; U.S. Pat. No. 5,175,312; U.S. Pat. No. 5,252,643; U.S. Pat. No. 5,216,052; U.S. Pat. No. 5,369,159; U.S. Pat. No. 5,488,117; U.S. Pat. No. 5,356,966; U.S. Pat. No. 5,367,008; U.S. Pat. No. 5,428,162; U.S. Pat. No. 5,428,177; and U.S. Pat. No. 5,516,920; which are hereby incorporated by reference.

For instance, benzofuranone type stabilizers which are particularly suitable include 3-[4-(2-acetoxyethoxy)phenyl]-5,7-di-tert-butyl-benzofuran-2-one; 5,7-di-tert-butyl-3-[4-(2-stearoyloxyethoxy)phenyl]benzofuran-2-one; 3,3′-bis[5,7-di-tert-butyl-3-(4-[2-hydroxyethoxy]-phenyl)benzofuran-2-one]; 5,7-di-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one; 3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butylbenzofuran-2-one; 3-(3,5-dimethyl-4-pivaloyloxy-phenyl)-5,7-di-tert-butyl-benzofuran-2-one; 5,7-di-tert-butyl-3-phenylbenzofuran-2-one; 5,7-di-tert-butyl-3-(3,4-dimethylphenyl)-benzofuran-2-one; or 5,7-di-tert-butyl-3-(2,3-dimethylphenyl)benzofuran-2-one.

The hindered amines are disclosed for example in U.S. Pat. Nos. 5,004,770, 5,204,473, 5,096,950, 5,300,544, 5,112,890, 5,124,378, 5,145,893, 5,216,156, 5,844,026, 5,980,783, 6,046,304, 6,117,995, 6,271,377, 6,297,299, 6,392,041, 6,376,584 and 6,472,456, and U.S. application Ser. No. 09/714,717, filed Nov. 16, 2000 and 10/485,377, filed Aug. 6, 2002. The relevant disclosures of these patents and applications are hereby incorporated by reference.

Suitable hindered amines include for example:

-   1) 1-cyclohexyloxy-2,2,6,6-tetramethyl-4-octadecylaminopiperidine, -   2) bis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate, -   3) bis(1-acetoxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate, -   4) bis(1,2,2,6,6-pentamethyl-4-yl)sebacate, -   5) bis(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate, -   6) bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate; -   7) bis(1-acyl-2,2,6,6-tetramethylpiperidin-4-yl)sebacate, -   8)     bis(1,2,2,6,6-pentamethyl-4-piperidyl)n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate -   9)     2,4-bis[(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-6-(2-hydroxyethylamino-s-triazine, -   10) bis(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)adipate, -   11)     2,4-bis[(1-cyclohexyloxy-2,2,6,6-piperidin-4-yl)butylamino]-6-chloro-s-triazine, -   12)     1-(2-hydroxy-2-methylpropoxy)-4-hydroxy-2,2,6,6-tetramethylpiperidine, -   13)     1-(2-hydroxy-2-methylpropoxy)-4-oxo-2,2,6,6-tetramethylpiperidine, -   14)     1-(2-hydroxy-2-methylpropoxy)-4-octadecanoyloxy-2,2,6,6-tetramethylpiperidine, -   15)     bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)sebacate, -   16)     bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)adipate, -   17)     2,4-bis{N-[1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl]-N-butyl-amino}-6-(2-hydroxyethylamino)-s-triazine, -   18) 4-benzoyl-2,2,6,6-tetramethylpiperidine, -   19)     di-(1,2,2,6,6-pentamethylpiperidin-4-yl)p-methoxybenzylidenemalonate, -   20) 4-stearyloxy-2,2,6,6-tetramethylpiperidine, -   21) bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)succinate, -   22) 1,2,2,6,6-pentamethyl-4-aminopiperidine, -   23)     2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4,5]decane, -   24) tris(2,2,6,6-tetramethyl-4-piperidyl)nitrilotriacetate, -   25)     tris(2-hydroxy-3-(amino-(2,2,6,6-tetramethylpiperidin-4-yl)propyl)nitrilotriacetate, -   26)     tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate, -   27)     tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate, -   28) 1,1′-(1,2-ethanediyl)-bis(3,3,5,5-tetramethylpiperazinone), -   29)     3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decan-2,4-dione, -   30)     8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione, -   31)     3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidin-2,5-dione, -   32)     3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione, -   33)     N,N′-bis-formyl-N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine, -   34) the reaction product of     2,4-bis[(1-cyclohexyloxy-2,2,6,6-piperidin-4-yl)butylamino]-6-chloro-s-triazine     with N,N′-bis(3-aminopropyl)ethylenediamine), -   35) the condensate of     1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and     succinic acid, -   36) linear or cyclic condensates of     N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and     4-tert-octylamino-2,6-dichloro-1,3,5-triazine, -   37) linear or cyclic condensates of     N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and     4-cyclohexylamino-2,6-dichloro-1,3,5-triazine, 38) linear or cyclic     condensates of     N,N′-bis-(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and     4-morpholino-2,6-dichloro-1,3,5-triazine, -   39) linear or cyclic condensates of     N,N′-bis-(1,2,2,6,6-pentamethyl-4-piperidyl)-hexamethylenediamine     and 4-morpholino-2,6-dichloro-1,3,5-triazine, -   40) the condensate of     2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazine     and 1,2-bis(3-aminopropylamino)ethane, -   41) the condensate of     2-chloro-4,6-di-(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazine     and 1,2-bis-(3-aminopropylamino)ethane, -   42) a reaction product of     7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro[4,5]decane     and epichlorohydrin, -   43) poly[methyl,     (3-oxy-(2,2,6,6-tetramethylpiperidin-4-yl)propyl)]siloxane,     CAS#182635-99-0, -   44) reaction product of maleic acid     anhydride-C₁₈-C₂₂-α-olefin-copolymer with     2,2,6,6-tetramethyl-4-aminopiperidine, -   45) the oligomeric compound which is the condensation product of     4,4′-hexamethylene-bis(amino-2,2,6,6-tetramethylpiperidine) and     2,4-dichloro-6-[(2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-s-triazine     end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine, -   46) the oligomeric compound which is the condensation product of     4,4′-hexamethylene-bis(amino-1,2,2,6,6-pentaamethylpiperidine) and     2,4-dichloro-6-[(1,2,2,6,6-pentaamethylpiperidin-4-yl)butylamino]-s-triazine     end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine, -   47) the oligomeric compound which is the condensation product of     4,4′-hexamethylene-bis(amino-1-propoxy-2,2,6,6-tetramethylpiperidine)     and     2,4-dichloro-6-[(1-propoxy-2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-s-triazine     end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine, -   48) the oligomeric compound which is the condensation product of     4,4′-hexamethylene-bis(amino-1-acyloxy-2,2,6,6-tetramethylpiperidine)     and     2,4-dichloro-6-[(1-acyloxy-2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-s-triazine     end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine and -   49) product obtained by reacting a product, obtained by reacting     1,2-bis(3-aminopropylamino)ethane with cyanuric chloride, with     (2,2,6,6-tetramethylpiperidin-4-yl)butylamine.

Also included are the sterically hindered N—H, N-methyl, N-methoxy, N-propoxy, N-octyloxy, N-cyclohexyloxy, N-acyloxy and N-(2-hydroxy-2-methylpropoxy) analogues of any of the above mentioned compounds. For example, replacing an N—H hindered amine with an N-methyl hindered amine would be employing the N-methyl analogue in place of the N—H.

The benzofuranone and hindered amine stabilizers are employed at the same levels as present components i) and ii).

The loss in stability of biodiesel may be observed by gum formation.

The following Examples illustrate the present invention. Unless otherwise indicated, parts and percentages are by weight.

EXAMPLES Rancimat Test

The Rancimat test, developed by the food industry, is employed to test the oxidative stability of soy biodiesel (methyl ester of soy fatty acid). A 3.0 g sample of soy biodiesel is held at 111.7° C. and exposed to a bubbling stream of air (10 liters per hour). The sample vessel is vented to a secondary container, where the off-gases are bubbled through 50 mL of distilled water. The test measures the volatile oxidation decomposition products such as peroxides, alcohols, aldehydes and carboxylic acids. The volatile decomposition products (chiefly formic acid) are swept through the sample vessel and vented into the secondary container where they are trapped by the distilled water. The conductivity of the water is constantly monitored as a function of time through use of an electrode. The inflection point (not a specific value) of the conductivity curve is the measured induction time. It should be pointed out that some samples will be highly conductive before the inflection point is achieved, while others will only be slightly conductive. An increase of the induction time indicates an increase in oxidative stability. Results are in the tables below.

Levels of additive are in weight percent based on the weight of the biodiesel.

The present stabilizer combination of components i) and ii) provide for outstanding performance for the Rancimat test.

A 6 hour induction time is necessary to meet the EN 14214 specification.

Rancimat Induction Time Induction Time additive (hours) none 4.0 2500 ppm A 10.9 2500 ppm P 10.3 2500 ppm Q 8.3 2500 ppm R 5.0

The above experiment is repeated where the biodiesel is spiked with 5 ppm of copper. The first control formulation contains no copper.

Rancimat Induction Time Induction Time sample additive (hours) (control - no Cu) none 6.2 (control) none 2.8 test 2500 ppm A 8.1 test 1500 ppm A 6.2 test  250 ppm S 4.1

Soy biodiesel is stored outdoors from Aug. 3, 2006 until Oct. 13, 2006 in Tarrytown, N.Y. The Rancimat induction times are monitored as a function of time (weeks) and additive level. The containers are closed and opened once per week for sampling. The following results are observed.

Rancimat Induction Time Induction Time Induction Time (hours) at Finish additive (hours) at Start (10 weeks) none 5.2 3.1 1000 ppm A 7.8 6.6 2500 ppm A 10.7 9.5

The experiments are repeated with other fatty acid methyl esters, rapeseed oil methyl ester, recycled cooking oil methyl ester and jatropha oil methyl ester. The following induction time results are found.

Rancimat Induction Time (hours) no 500 ppm 1000 ppm 2500 ppm sample additive A additive A additive A additive A rapeseed oil 3.6 6.2 7.2 not performed recycled cooking oil 1.9 5.7 9.1 not performed jatropha oil 1.9 2.8 4.5 7.0

Further rancimat induction time experiments in soy biodiesel are performed.

Rancimat Induction Time Induction Time additive (hours) none 4.4 2788 ppm A 9.5 2788 ppm B 9.5 2788 ppm C 7.9 2788 ppm D 4.2 2500 ppm P 9.3 2500 ppm Q 7.8 2500 ppm R 4.0 2500 ppm S 4.4 2500 ppm T 9.4

These experiments are repeated with soy biodiesel spiked with 0.25 ppm Fe naphthenate and with 0.01 ppm Cu naphthenate.

Rancimat Induction Time Induction Time Induction Time (hours) (hours) additive 0.25 Fe spike 0.01 Cu spike none 3.2 2.8 2788 ppm A 8.7 7.6 2788 ppm B 8.2 7.4 2788 ppm C 7.9 6.8 2788 ppm D 3.6 3.2 2500 ppm P 7.9 6.4 2500 ppm Q 7.5 6.4 2500 ppm R 3.4 2.8 2500 ppm S 4.8 3.2 2500 ppm T 7.8 6.6

Experiments are performed on a blend B20, 20% soy biodiesel and 80 petroleum diesel and on B20 spiked with 1 ppm Cu naphthenate.

Rancimat Induction Time Induction Time Induction Time (hours) (hours) B20 blend with additive B20 blend 1 ppm Cu spike none 10.6 1.2 1000 ppm A 33.5 4.5 1000 ppm G 29.1 4.2 1000 ppm H 33.0 3.9

Experiments are performed in soy bioediesel spiked with different levels of Cu acetate. Induction time is in hours.

Rancimat Induction Time (hours) additive no metal 0.25 ppm Cu 0.5 ppm Cu 1 ppm Cu none 4.2 0.40 0.13 0.15 1000 ppm E 0.15 1000 ppm F 0.78

Experiments are performed with soy biodiesel contaminated with mixed metals. The mixed metal spike is 0.00006 ppm Cu naphthenate and 0.0032 ppm Fe naphthenate.

Rancimat Induction Time Induction Time Induction Time (hours) mixed additive (hours) metal spike none 4.3 2.3 Additive S 4.5 2.0 Additive U 4.6 2.9 Additive E 6.7 3.5

Additives:

Additive P butylated hydroxytoluene (BHT) Additive Q 2,6-di-tert-butylphenol Additive R vitamin E Additive S mixture of 4-(and 5)-methyl-1-(di(2-ethylhexyl)-aminomethyl)-benzotriazole

Additive T

-   -   41% by weight         tetrakis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionyloxymethyl)methane     -   29% by weight 2,6-di-tert-butylphenol     -   30% by weight methyl         3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate         Additive U 1-(di-(2-ethylhexyl)aminomethyl) 1,2,4-triazole

Additive Mixtures of the Present Invention: Additive A 90% Additive T

-   -   10% Additive S

Additive B 90% Additive P

-   -   10% Additive S

Additive C 90% Additive Q

-   -   10% Additive S

Additive D 90% Additive R

-   -   10% Additive S

Additive E 89% Additive T

-   -   11% Additive S

Additive F 89% Additive T

-   -   11% Additive U

Additive G 86% Additive T

-   -   14% Additive S

Additive H 86% Additive T

-   -   14% Additive U 

1. A biodiesel fuel composition stabilized against the deleterious effects of heat, light, oxygen and metals, which composition comprises a biodiesel fuel and an effective stabilizing amount of a combination of i) one or more compounds selected from the group consisting of the sterically hindered phenolic antioxidants and ii) one or more compounds selected from the group consisting of the triazole metal deactivators.
 2. A composition according to claim 1 comprising one or more phenolic antioxidants selected from the group consisting of butylated phenol, butylated hydroxytoluene, butylated hydroxyanisole, tocopherol, benzylphosphonates, esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with mono- or polyhydric alcohols, esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols and esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or polyhydric alcohols.
 3. A composition according to claim 1 comprising one or more hindered phenolic antioxidants selected from the group consisting of 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol (BHT), 2,2′-methylene bis-(4,6-di-tert-butylphenol), 1,6-hexamethylene-bis-(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), ((3,5-bis(1,1-dimethylethyl)-4-hydroxphenyl)methylthio)acetic acid C₁₀-C₁₄ isoalkyl esters, 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid C₆-C₉alkyl esters, 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid methyl ester, tetrakis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionyloxymethyl)methane, thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate and 2,5-di-tert-butylhydroquinone.
 4. A composition according to claim 1 comprising one or more hindered phenolic antioxidants selected from the group consisting of 2,6-di-tert-butylphenol, 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid methyl ester and tetrakis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionyloxymethyl)methane.
 5. A composition according to claim 1 comprising one or more triazole metal deactivators selected from compounds of the formula

where R₁ and R₂ are the same or different and are hydrogen, C₁-C₂₀alkyl, C₃-C₂₀alkenyl, C₅-C₁₂cycloalkyl, C₇-C₁₃aralkyl, C₆-C₁₀aryl or hydroxy or R₁ and R₂, together with the nitrogen atom to which they are each attached may form a 5-, 6- or 7-membered heterocylic ring, or R₁ and R₂ are a group of formula R₃X[(—R₄—)O]_(n)(—R₄)— where X is O, S or NR₃, R₃ is hydrogen or C₁-C₂₀alkyl, R₄ is C₁-C₁₂alkylene, n is 0 or an integer from 1 to 6, or one of R₁ and R₂ is a group of formula

or R₂ is a group of formula (II) and R₁ is a group of formula [R₄]_(n)—N(R₅)-A-[N(R₅)₂]_(m) where m is 0 or 1 and, when m is zero, A is a group of formula (II) and, when m is 1, A is alkylene or C₆-C₁₀ arylene and R₅ is a group of formula (II).
 6. A composition according to claim 5 comprising one or more triazole metal deactivators selected from the group consisting of 1-(or 4)-(dimethylaminomethyl)triazole, 1-(or 4)-(diethylaminomethyl)triazole, 1-(or 4)-(di-isopropylaminomethyl)triazole, 1-(or 4)-(di-n-butylaminomethyl)triazole, 1-(or 4)-(di-n-hexylaminomethyl)triazole, 1-(or 4)-(di-isooctylaminomethyl)triazole, 1-(or 4)-(di-(2-ethylhexyl)aminomethyl)triazole, 1-(or 4)-(di-n-octylaminomethyl)triazole, 1-(or 4)-(di-n-decylaminomethyl)triazole, 1-(or 4)-(di-n-dodecylaminomethyl)triazole, 1-(or 4)-(di-n-octadecylaminomethyl)triazole, 1-(or 4)-(di-n-eicosylaminomethyl)triazole, 1-(or 4)-[di-(prop-2′-enyl)aminomethyl]triazole, 1-(or 4)-[di-(but-2′-enyl)aminomethyl]triazole, 1-(or 4)-[di-(eicos-2′-enyl)aminomethyl]triazole, 1-(or 4)-(di-cyclohexylaminomethyl)triazole, 1-(or 4)-(di-benzylaminomethyl)triazole, 1-(or 4)-(di-phenylaminomethyl)triazole, 1-(or 4)-(4′-morpholinomethyl)triazole, 1-(or 4)-(1′-pyrrolidinomethyl)triazole, 1-(or 4)-(1′-piperidinomethyl)triazole, 1-(or 4)-(1′-perhydroroazepinomethyl)triazole, 1-(or 4)-(2′,2″-dihydroxyethyl)aminomethyl]triazole, 1-(or 4)-(dibutoxypropyl-aminomethyl)triazole, 1-(or 4)-(dibutylthiopropyl-aminomethyl)triazole, 1-(or 4)-(di-butylaminopropyl-aminomethyl)triazole, N,N-bis-(1- or 4-triazolylmethyl)laurylamine, N,N-bis-(1- or 4-triazolylmethyl)oleylamine, N,N-bis-(1- or 4-triazolylmethyl)ethanolamine and N,N,N′,N′-tetra(1- or 4-triazolylmethyl)ethylene diamine.
 7. A composition according to claim 5 comprising 1-(di-isooctylaminomethyl)-1,2,4-triazole or 1-(di-(2-ethylhexyl)aminomethyl) 1,2,4-triazole.
 8. A composition according to claim 1 comprising one or more triazole metal deactivators selected from compounds of the formula

where R₆ is C₁-C₁₂alkyl, R₇ is C₁-C₁₂alkyl, C₁-C₁₂alkyl interrupted by one or more O atoms or is C₅-C₁₂cycloalkyl and R⁸ and R⁹ are hydrogen or methyl.
 9. A composition according to claim 8 comprising one or more triazole metal deactivators selected from the group consisting of 1-(2-methoxyprop-2-yl)tolyltriazole, 1-(1-methoxyethyl)tolyltriazole, 1-(1-methoxpropyl)tolyltriazole, 1-(1-isobutoxybutyl)tolyltriazole, 1-(1-tert-butoxybutyl)tolyltriazole, 1-(1-hexyloxybutyl)tolyltriazole, 1-(1-octyloxybutyl)tolyltriazole, 1-(1-butoxy-2-methylpropyl)tolyltriazole, 1-(1-dodecyloxybutyl)tolyltriazole, 1-(1-isopropyloxyethyl)tolyltriazole, 1-(1-isopropyloxypropyl)tolyltriazole, 1-(1-isopropyloxybutyl)tolyltriazole, 1-(1-cyclohexyloxypropyl)tolyltriazole, 1-(1-cyclohexyloxyheptyl)tolyltriazole, 1-(1-cyclohexyloxybutyl)tolyltriazole, 1-[1-(2-methoxyethoxy)butyl]tolyltriazole and 1-[1-(2-ethoxyethoxy)butyl]tolyltriazole.
 10. A composition according to claim 8 comprising 1-(2-methoxyprop-2-yl)tolyltriazole, 1-(1-cyclohexyloxypropyl)tolyltriazole, 1-(1-cyclohexyloxyheptyl)tolyltriazole or 1-(1-cyclohexyloxybutyl)tolyltriazole.
 11. A composition according to claim 1 comprising one or more triazole metal deactivators selected from compounds of the formula

where R₁₀ is hydrogen or C₁-C₁₂alkyl, R₁₁ at and R₁₂ are the same or different and are hydrogen, C₁-C₂₀alkyl, C₃-C₂₀alkenyl, C₅-C₁₂cycloalkyl, C₇-C₁₃aralkyl, C₆-C₁₀aryl or hydroxy or R₁₁ and R₁₂, together with the nitrogen atom to which they are each attached may form a 5-, 6- or 7-membered heterocylic ring, or R₁₁ and R₁₂ are a group of formula R₁₃X[(—R₁₄—)O]_(n)(—R₁₄)— where X is O, S or NR₁₃, R₁₃ is hydrogen or C₁-C₂₀alkyl, R₁₄ is C₁-C₁₂alkylene, n is 0 or an integer from 1 to 6, or one of R₁₁ and R₁₂ is a group of formula

or R₁₂ is a group of formula (II) and R₁₁ is a group of formula —[R₁₄]_(n)—N(R₁₅)-A-[N(R₁₅)₂]_(m) where m is 0 or 1 and, when m is zero, A is a group of formula (II) and, when m is 1, A is alkylene or C₆-C₁₀arylene and R₁₅ is a group of formula (II).
 12. A composition according to claim 11 comprising one or more triazole metal deactivators selected from the group consisting of 4-(or 5)-methyl-1-(di(2-ethylhexyl)-aminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(dimethylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(diethylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(di-isopropylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(di-n-butylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(di-n-hexylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(di-isooctylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(di-n-octylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(di-n-decylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(di-n-dodecylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(di-n-octadecylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(di-n-eicosylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-[di-(prop-2′-enyl)aminomethyl]-benzotriazole, 4-(or 5)-methyl-1-[di-(but-2′-enyl)aminomethyl]-benzotriazole, 4-(or 5)-methyl-1-[di-(eicos-2′-enyl)aminomethyl]-benzotriazole, 4-(or 5)-methyl-1-(di-cyclohexylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(di-benzylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(di-phenylaminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(4′-morpholinomethyl)-benzotriazole, 4-(or 5)-methyl-1-(1′-pyrrolidinomethyl)-benzotriazole, 4-(or 5)-methyl-1-(1′-piperidinomethyl)-benzotriazole, 4-(or 5)-methyl-1-(1′-perhydroroazepinomethyl)-benzotriazole, 4-(or 5)-methyl-1-(2′,2″-dihydroxyethyl)aminomethyl]-benzotriazole, 4-(or 5)-methyl-1-(dibutoxypropyl-aminomethyl)-benzotriazole, 4-(or 5)-methyl-1-(dibutylthiopropyl-aminomethyl)-benzotriazole and 4-(or 5)-methyl-1-(di-butylaminopropyl-aminomethyl)-benzotriazole.
 13. A composition according to claim 11 comprising 4-(or 5)-methyl-1-(di(2-ethylhexyl)-aminomethyl)-benzotriazole or 4-(or 5)-methyl-1-(di-isooctylaminomethyl)-benzotriazole.
 14. A composition according to claim 1 comprising one or more hindered phenolic antioxidants selected from the group consisting of 2,6-di-tert-butylphenol, 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid methyl ester and tetrakis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionyloxymethyl)methane and one or more triazole metal deactivators selected from the group consisting of 1-(di-isooctylaminomethyl)-1,2,4-triazole, 1-(di-(2-ethylhexyl)aminomethyl) 1,2,4-triazole, 1-(2-methoxyprop-2-yl)tolyltriazole, 1-(1-cyclohexyloxypropyl)tolyltriazole, 1-(1-cyclohexyloxyheptyl)tolyltriazole, 1-(1-cyclohexyloxybutyl)tolyltriazole, 4-(or 5)-methyl-1-(di(2-ethylhexyl)-aminomethyl)-benzotriazole and 4-(or 5)-methyl-1-(di-isooctylaminomethyl)-benzotriazole.
 15. A composition according to claim 1 further comprising one or more stabilizers selected from the group consisting of the 3-arylbenzofuranone stabilizers and the hindered amine light stabilizers.
 16. A composition according to claim 1 where the components i) and ii) each are present at levels of about 5 ppm to about 5000 ppm.
 17. A composition according to claim 1 where the components i) and ii) each are present at levels of about 50 ppm to about 5000 ppm.
 18. A process for the stabilization of a biodiesel fuel against the deleterious effects of heat, light, oxygen and metals, which process comprises incorporating into a biodiesel fuel an effective stabilizing amount of a combination of i) one or more compounds selected from the group consisting of the sterically hindered phenolic antioxidants and ii) one or more compounds selected from the group consisting of the triazole metal deactivators.
 19. A composition according to claim 1 further comprising one or more compounds selected from the group consisting of the metal chelating compounds. 